[eric woodall]

Two quick questions:

1. During the summer the floor in the bathroom furthest from the hvac unit (at the end of the vent run) buckles up slightly. I have noticed this is where I see most the condensation drips from the ductwork under the house. I think this is because there is not enough insulation on the duct. Has anyone run into this problem? And if so, how do I correct it?

2. Would I benefit from enlarging the present vent size from 4 x 8" to 4" x 12" or larger? I am very capable of doing this type of work. Thank you for any replies!!

 

[joecaption]

Ok so what type flooring do you have?

Is there a crawl space of full basement?

If it's a crawl space is there a 6 mil. vaper barrer on the ground?

Has the rim joist been sealed and insulated?

Is there any insulation under the floors?

How wet is it under the house? Standing water or always wet under there = mold, fungus and flooring problums.

 

[eric woodall]

aspects of flooring

Home is a 1983 Wycks doublewide on a permanent block foundation with block supports every seven feet under the house with steel rods welded to the steel frame rails and sunk in concrete inside these block supports. Floor above bathroom vent is particleboard; no basement area, just a crawlspace. No vapor barrier in the crawlspace. I do not know how much insulation is around the square ac ducting because I have not cut into the road barrier yet to see. I have noticed the insulation has fallen directly beneath the branch duct where it attaches to the hvac inside unit. Any answers?

 

[joecaption]

Partical boad soaks up moisture like a sponge, even from just in the air. When it gets wet it expands, I've seen it double in size.
Adding that vaper barrier under the home is is about all you can do short of replacing the subflooring.

 

[eric woodall]

crawlspace update

P.S.

I am not sure what you mean by the rim joist being sealed; if you mean the floor joists around the vent, I am sure all they have is the road barrier for a seal. And there is no standing water under the house that I can see; the crawlspace is vented year around, which I have heard is not really a good thing!!

 

[joecaption]

Depends on where you live.
Really need to go back and add your location to your profile.
There was no mention of it being a double wide in your first post that's why I was making the suggestions I did.

 

[eric woodall]

update

We live in Notasulga, Alabama, 10 miles from Auburn University. You still made some excellent suggestions, though. I was planning on remodeling the bathroom anyhow, replacing the particleboard with 3/4" plywood topped with 1/2" tileboard and tile. I just am not sure what I should be insulating the air conditioning duct with. I have heard that if you install paper-faced insulation to the joists below the duct you can have mold problems from moisture being trapped in the insulation. Any answers?

 

[joecaption]

I'd use Advantec T & G for subflooring not plywood. Advantec is stronger and far more moisture resistant, will never delaminiate.
I also would never suggest installing tile in any mobile home! Far to many things that flex involve. There can be no movement at all when working with tile.
Use sheet goods instead if you want it to hold up.